An international team of scientists has developed a chaos-assisted computational spectrometer that breaks the long-standing trade-off between size, resolution, and bandwidth – achieving performance previously thought impossible in such a compact device.
Described in Light: Science & Applications, the new on-chip spectrometer spans just 20 × 22 μm², yet offers a remarkable spectral resolution of 10 picometers across a 100 nm bandwidth. “We attained a record-high bandwidth-to-resolution ratio per footprint,” said Yikai Su from Shanghai Jiao Tong University, who co-led the work with Xuhan Guo.
The breakthrough relies on controlled chaos. Traditional spectrometers often use periodic structures like gratings, which limit flexibility and miniaturization. Instead, Su’s team used a deformed microcavity shaped as a Limaçon of Pascal – a design that supports chaotic light propagation and breaks the resonant periodicity typical in symmetric microdisks. This chaotic mode mixing creates a highly diverse and decorrelated response matrix essential for computational spectral reconstruction.
“Chaotic systems are typically avoided due to their unpredictability,” Su noted. “But here, chaos becomes a feature, not a bug – it supplies the random sampling behavior critical to our spectrometer’s performance.”
By training a reconstruction algorithm with the device’s unique spectral fingerprints, the team could deconvolute complex input spectra from the compact chip. Compared to conventional computational spectrometers, the device operates with lower power consumption – just 16.5 mW – and avoids bulky cascaded structures.
The authors also demonstrated adaptability: replacing grating couplers with edge couplers extended the operational bandwidth beyond 300 nm. And by resizing the chaotic cavity, the system can be tuned across silicon’s transparent window or ported to alternative photonic materials.
“Our design provides a viable technical path for portable, low-power spectral sensing,” the team concluded. They suggest that such on-chip systems could extend high-resolution spectral analysis beyond the laboratory, enabling chemical and biomedical sensing in real-world environments.
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